1. Field of the Invention
This invention relates a thin film-structure and a method for producing the same, and more particularly the same structure and the same method suitable for parts constituting micro machines such as a micro actuator, cats, various sensors such as a micro sensor, various probes such as a sensor for a scanning probe-microscope, etc.
2. Description of the Prior Art
Micro machines, various sensors, various probes, etc. are needed to detect outward powers from a substrate surface, various proximity effects in a substrate surface, flows of liquids, voltages of other electronic circuits. Thus, thin film-structures, made by three-dimensionally deforming plane structures such as beams composed of various thin films through applied micro machining of thin film-forming techniques and micro processing techniques in manufacturing semiconductors, have been used.
In the past, a thin film-structure was produced as follows:
(1) A plane structure composed of two kind and over layers with different thermal expansion coefficients is formed and the three-dimensional thin film-structure was produced from the plane structure through its bimorph effect.
(2) A plane structure made of polysilicon is heated and deformed through current heating, maintained by a micro probe, to produce the three-dimensional thin film-structure.
(3) A thin film is formed by sputtering or the like and the three-dimensional thin film-structure is produced from the thin film by taking advantage of the remaining stresses in the film formation.
In producing the thin film structure by taking advantage of the above bimorph effect (the above (1)), the thin film structure has had layers with different thermal expansion coefficient after its production. Thus, on account of temperature change in using, the shape of the thin film structure changes with time through the bimorph effect in nearby room temperature.
In producing the thin film structure by heating and deforming the polysilicon (the above (2)), the thin film structure has difficulty having a desired strength and elastic limit, etc. because a material for it is limited to the polysilicon. Moreover, the plane structure requires to be held by a microprobe, which results in degradation of its productivity.
In producing the thin film structure by taking advantage of the remaining stresses in film-forming (the above (3)), its reproducibility is degraded and its shape change with time due to the change with time of the remaining stresses.